A thermal protecting coating was prepared at 1200 ℃ using TaSi₂, MoSi₂, borosilicate glass powders as the starting materials. Subsequently the thermal protecting coating was heated at 1650℃ for 2 min and cooled naturally to room temperature. The microstructures and composition of the thermal protecting coating before and after heated at 1650℃ were measured by XRD, SEM and EDS. It is found that the surface of the as-prepared thermal protecting coating contained Ta₂O₅ and small amount of TaSi₂. Lots of Ta₂O₅ sheets were formed in the heating center region of the coating surface after the heating of 1650℃. The section of the coating close to the surface became dense after heating at 1650℃, and the thickness of the dense section was about 23 μm. There is an even distribution for Ta and Mo elements in the element mapping of coating section, that is, the composition of the thermal protecting coating is uniformed.